docs: def units(self):
          """Units."""
          if "units" in self.attrs.keys():
              # This try-except here for compatibility with v1.0.0 of WT5 format
              try:
                  self.attrs["units"] = self.attrs["units"].decode()
              except AttributeError:
                  pass  # already a string, not bytes
              return self.attrs["units"]
          return None